1. Field of the Invention
The present invention relates to a rack and pinion steering gear for steering the steerable wheels of a vehicle.
2. Description of the Prior Art
Rack and pinion steering gears for vehicles are known. U.S. Pat. No. 3,834,727 discloses an end take-off rack and pinion steering gear. The steering gear includes a rack housing supporting a rack member for axial movement. A pinion gear, connected with a steering wheel of the vehicle, meshingly engages with rack teeth formed in the rack member. The rack member moves relative to the rack housing in response to rotation of the pinion gear. A respective one of a pair of tie rods is connected to each axial end portion of the rack member. The tie rods move to steer the steerable wheels of the vehicle in response to movement of the rack member.
U.S. Pat. No. 4,479,400 discloses a center take-off hydraulic power assist rack and pinion steering gear. The steering gear includes a rack housing supporting a rack member for axial movement. A piston is connected to an axial end portion of the rack member. The piston slides within the rack housing and defines a pair of power assist chambers. A longitudinally extending opening is centrally located in the rack housing. A slide member is connected to the rack member and extends through the opening in the rack housing. Tie rods are attached to the slide member, and thus move to steer the vehicle upon movement of the rack member.
These known rack and pinion steering gears are relatively light in weight and relatively easy to install on the vehicle. However, the locations at which the tie rods are attached to the rack member are limited by the design of the steering gears. The locations may not permit steering of certain vehicles according to a principle known as "Ackerman steering". Ackerman steering is defined as all of the wheels of a vehicle turning through concentric arcs during steering. Thus, Ackerman steering minimizes wear on tires of the vehicle. Further, since in the prior art the locations at which the tie rods are attached to the rack member are limited, "bump steer" may not be minimized.